THE COURSE OF BIOLOGIC EVOLUTION. 49 



tology, both vegetable and animal, thus doubly confirms the 

 view that fruits, in the sense here employed, had their origin 

 simultaneously with the appearance of birds, as flowers did 

 with that of flower-frequenting insects, toward the close of 

 Mesozoic time. Attracted by their bright colors correlated 

 with pleasant flavors, birds learned to visit the plants that bore 

 such fruits. Flying thence to distant parts and voiding the 

 hard seeds of berries and stones of drupes, they became the 

 effective instruments for the dissemination of these forms. 



The great problem of distribution was thus solved by bird 

 life as was that of cross-fertilization by insect life, and just as 

 plants vied with one another to attract insects to their flowers, 

 so did they also vie with one another to attract birds to their 

 fruits. Here again it was the universal esthetic faculty that 

 enabled the ancient bird life to prepare the earth for human 

 habitation, and yet, no more than in the previous case was 

 man the final cause. So uniform is the standard of taste 

 throughout the psychic world that what contributes to the 

 pleasure of a bird or an insect also supplies some esthetic want 

 in the race of men. 



ABNORMALITIES OF SEX. 



* 



There is one other abnormal or supra-normal influence in the 

 organic world which is so important and so well illustrates the 

 principle now under consideration, that it seems proper briefly 

 to advert to it. I refer to the causes which in many cases, par- 

 ticularly in the animal kingdom, make one sex differ so widely 

 from the other. 



An array of facts taken from asexual life and from the very 

 early stages of sexuality converge to show that primarily and 

 normally the female is the main trunk line of development, 



